There are a number of surgical procedures which involve the delivery of medication and other fluids into the bone of a patient. One example is intraosseous infusion, a procedure for administering fluids into a patient's bloodstream through the medullary cavity of a patient's bones, typically the long bones, jaw bone or pelvis. This procedure allows the medication or other fluids to enter the bloodstream from the medullary cavity within seconds without requiring access to a suitable blood vessel of the patient. In other applications, medication or other fluids are delivered to the cortical plate of patients' bones.
A type of device which is used to deliver fluids into bone is a delivery pin or needle. A delivery needle is used in intraosseous infusion for accessing the medullary cavity of the bone. The needle has a passageway and a number of orifices in communication with the passageway for delivering the fluids into the bone. For boring through bone, the needle has a pointed end and a number of threads spaced longitudinally along the needle. The pointed end may include a self-cutting tip for tapping into and boring into bone. A drill may be used to drill a hole in the bone prior to inserting the needle, if no self-cutting tip is provided. The needle is inserted by rotating the needle with either a drill operated at a low speed, or manually. The needle is inserted until the orifices are appropriately positioned within the patient's bone.
The orifices of delivery pins have a tendency to become clogged with tissue during the advancement of the needle through the bone. U.S. Pat. No. 5,601,559 to Melker et al., the disclosure of which is hereby incorporated by reference herein, discloses orifices which are sized and positioned with respect to threads on the needle to avoid such clogging. Clogging of the orifices of the pin prevents the administration of fluids and may present a possibly life-threatening situation for a patient in dire need of the administration of such fluids.
Threaded pins are also used as fixation devices anchoring other devices to bone. For example, one device for anchoring prostheses in bone includes cutting edges for boring into bone, as well as orifices for providing space into which bone tissue can grow. Such a device is disclosed by Branemark, U.S. Pat. No. 5,725,581, the disclosure of which is hereby incorporated by reference herein. In these devices as well, bone tissue tends to clog the orifices as the pin advances through the bone. Thus, improvements in needles or pins for delivering medication and other fluids to the bone of a patient are desirable.